5.1 - Worksheet #1 - Coulomb’s Law Questions
Minimum: 1-6 Challenge: 7
1. A helium nucleus has charge +2e and a neon nucleus +10e, where e =
1.602 x 10-19 coul. With what force do they repel each other when
separated by 3.00 x 10-9 meters?
2. If two equal charges, each of 1.00 coulomb, were separated in air by a distance of
1.00 km, what would be the force between them?
3. Determine the force between two free electrons spaced 1 angstrom (1.0 x 10-10 m) apart.
4. What is the force of repulsion between two argon nuclei when separated by 1
millimicron (1.0 x 10-9 m)? The charge on an argon nucleus is +18e.
5. Two equally charged pith balls are 3 cm apart in air and repel each other with a force
of 4 x 10-5 N. Compute the charge on each ball.
6. Two small equal pith balls are 3.0 cm apart in air and carry charges of +3.0 x 10-9 and
–12 x 10-9 C respectively. Compute the force of attraction.
7. The normal hydrogen atom consists of a proton nucleus and an orbital electron, each
carrying the fundamental charge of magnitude e = 1.602 x 10-19 C. Assuming that the
electron orbit is circular and the separation between the particles is 5.3 x 10-11 meters,
find:
a) the force of electrical attraction between the particles
b) the gravitational force of attraction between them
c) which force is larger? How many times?
(mass e- = 9.11 x 10-31 kg ; p+ = 1.67 x 10-27 kg)
8.
+5e
-4e
2 cm
1 cm
What is the net force on
the sphere having charge
of –4e?
+2e
9. Charges of +2, +3 and –8 microcoulombs are placed in air at the vertices of an
equilateral triangle of side 10 cm. Calculate the magnitude of the force acting on the
-8µc due to the other two charges.
(1 microcoulomb (1 µc) = 1 x 10-6 C)
Answers for Coulomb’s Law Questions
5.13 x 10-10 N
8990 N repulsion
2.3 x 10-8 N repulsion
7.46 x 10-8 N
2 x 10-9 C
3.6 x 10 –4 N
a) 8.2 x 10-8 N
b) 3.6 x 10-47 N
c) Electrical force 2.3 x 10-47 times greater
8. Fnet = 2.16 x 10-23 N L58°D
9. 31.1 N
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